The results bolster the World Health Organization recommendation that an oral dose of vitamin A be given for two consecutive days to children who live in areas where vitamin A deficiency may exist. However, the study also found that a single megadose of vitamin A is not effective, although still being used in some parts of the world, according to lead researcher Yang Huiming, associate professor of pediatrics at Sichuan University in China.

Huiming and colleagues looked at eight trials encompassing 2,574 participants age 15 and under. Six of the studies were done in Africa, one in Japan and one in England. Pneumonia was most common cause of death in children with measles in the four studies that specified cause. Pooling data from studies that used two doses of vitamin A, comprising 429 hospitalized children, the reviewers found a 67 percent reduction of mortality from pneumonia.

However, when taking into account all studies, which included outpatients with mild disease, vitamin A did not significantly reduce measles-related mortality for children above age 2. Vitamin A cut the risk of post-measles croup by 41 percent (722 children studied), and of the two studies that addressed post-measles diarrhea (474 children), the one using two doses of vitamin A showed a 65 percent lower risk of developing diarrhea, while the single-dose study did not show reduction.